1. Field of the Invention
The present invention relates generally to the field of air cooling and heating systems and related devices for buildings such as homes. More specifically the present invention relates to a filter status monitoring method and to an apparatus for practicing the method. The apparatus includes an electronic circuit which generates a signal to remind the home owner or service person to replace the filter in the air handler of an attached heating or cooling system, and which shuts down the system to prevent compressor damage. The apparatus further includes fire detection and occupant alerting means; low coolant level, low battery voltage, condensation and open door detection means; computer connection software and emergency telephone call placing means.
2. Description of the Prior Art
There have previously been devices for alerting an operator to the need to change a filter in an air temperature control system. These devices are intended to maximize operating efficiency, and prevent the filter from becoming clogged and thereby damaging the system compressor.
Mason, U.S. Pat. No. 3,936,284, issued on Feb. 3, 1976, discloses an air filtering apparatus using a prefilter and a final filter for filtering air passing through the apparatus. The apparatus includes a chamber having an inlet and an outlet. A first, or prefilter is disposed across the chamber inlet and a second or final filter is disposed across the chamber outlet. A divider, preferably in the form of a wall, is disposed between the two filters and divides the chamber into two adjacent sub-chambers, and this wall has an opening through which air may pass from the first, or inlet, subchamber into the second, or outlet, subchamber. A blower is also disposed between the two filters is provided for forcibly blowing air from the first subchamber into the second subchamber. Mason further provides an integrated signaling device which monitors both filters and independently signals when one or the other of these filters has accumulated sufficient particulates from the air to require replacement. The concentration of particulate matter in the filter is determined by monitoring pressure differential between the high and low sides of each filter. A problem with Mason is that the filter monitoring mechanism is complex and costly.
Lobdell, U.S. Pat. No. 5,428,964, issued on Jul. 4, 1995, reveals a control for an air quality machine. Lobdell monitors in real-time the quality of air in a work or living space, and includes a portable electronic monitoring device which senses and indicates air quality within a given space. Within its housing the device has a particular sensor for detecting the ambient concentration of aerosols and particulates in the space and for comparing the detected level with a predetermined particulates threshold limit value (TLV). When a particulate level is detected above the TLV, an LED illuminates to indicate that the air quality has become marginal or unacceptable. Air passes through mechanical prefilter media for collection of larger airborne contaminants, then through an ionization section and electrostatic charged grid, mesh, or media for removal of microscopic particulates from the air stream. Once again, the pressure differentials between opposing sides of each system filter are monitored to determine when filter changing is needed, as in Mason.
Asano, et al., U.S. Pat. No. 5,205,156, issued on Apr. 27, 1993, teaches a device for detection of the degree of clogging of a dust filter. In Asano, et al., the air speed on the downstream side of a filter is monitored, and when the detected speed reads too low, the filter is to be replaced. The problems of Mason are again presented.
Other related art includes Kokatsu, U.S. Pat. No. 5,236,477, for a microcomputer-based control device; Maly, et al., U.S. Pat. No. 5,378,254, for a filter sensing apparatus and filter; and Comer, U.S. Pat. No. 5,461,368, for an air filter monitoring device in a system using a multi-speed blower. These prior devices all fail to teach selectable monitored time periods for filter replacement and system shut-down if the filter is not replaced to prevent system damage.
It is thus an object of the present invention to provide reminder apparatus and method for alerting an operator to the need to change a system filter and thus prevent resulting service calls.
It is another object of the present invention to provide such an apparatus and method which permit the operator selection of a primary filter replacement period appropriate to the particular system, and which alerts the operator at the end of the primary filter replacement period.
It is still another object of the present invention to provide such an apparatus and method which shut down the system at the end of a secondary filter replacement period to protect the compressor from damage, if the filter is not replaced.
It is a further object of the present invention to provide such an apparatus and method which include an apparatus program providing means for operator testing of the program and signalling mechanisms.
It is a still further object of the present invention to provide such an apparatus which includes means for alerting a building occupant or other appropriate person of a fire, low coolant level, low battery power, an open door or window or condensation in the system condensation pan and, in some instances, shut down the system to protect the system and building.
It is an additional object of the present invention to provide such an apparatus which includes means for connection to and operation from a computer and monitor.
It is finally an object of the present invention to provide such an apparatus which is economical to manufacture, easy to install and operate, and highly reliable.